<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<canvas id="canvas" height="500" width="500" style="border: 1px solid red;"></canvas>
	</body>
	<script type="text/javascript">
		function b(){
			var context = document.getElementById("canvas").getContext("2d");
			context.strokeRect(0,0,300,300);
//			context.arc(100,100,50,Math.PI/180*270,Math.PI/180*180,true);
			context.arc(100,100,50,Math.PI/180*180,Math.PI/180*270,false);
			context.stroke();
		}
		window.addEventListener("load",b,true);
	</script>
</html>
